Gas-phase C/O ratio as a function of distance to the star for the two different values of the stellar mass (M_∗ = 1, 0.1 M_⊙) and three values of the turbulent viscosity (α = 10⁻², 10⁻³, 10⁻⁴). The horizontal dashed grey line represents the initial C/O ratio. The sublimation lines of the main species contributing to the C/O ratio are indicated with vertical lines. We see that the evolution of the gas-phase C/O ratio does not change significantly with varying disc turbulence (α > 10⁻³) and stellar mass. However, in the α = 10⁻⁴ case, where the pebble flux is intense and diffusion is slow, the variations in gas-phase C/O ratio are greater. Once the pebble flux runs out, viscous flows govern the evolution of the gas-phase C/O ratio, leading to differences depending on stellar mass.